Manufacturing process of rubber layered structure

ABSTRACT

A rubber layered structure used for a weather strip or a glass run, which includes an EPDM rubber base and an ornamental surface layer or a functional surface layer for enhancing slidability of a door glass. An ornamental or functional surface layer is stuck to an EPDM rubber base with a laminated film. The laminated film includes a first layer of an olefin resin with polar functional groups and a second layer of a polar thermoplastic resin. The first layer, which includes a non-polar olefin resin and polar functional groups, adheres to both the EPDM rubber base and the second layer of a polar resin such as polyester. The second layer securely adheres to the surface layer.

This is a division of application Ser. No. 08/227,988, filed Apr. 15,1994, now U.S. Pat. No. 5,489,461 which was a continuation ofapplication Ser. No. 08/126,740, filed Sep. 27, 1993, abandoned; whichwas a continuation of application Ser. No. 07/793,730, filed Nov. 21,1991, abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rubber layered structure, and moreparticularly to a structure for attaching to the periphery of openingsof an automobile. The rubber layered structure includes an EPDM rubberbase and a surface layer such as an ornamental layer or a layer forenhancing the slidability of window glass.

2. Description of the Related Art

EPDM (ethylene-propylene non-conjugated diene copolymer) rubber iswidely used for automobile parts which require good resistance toweather, ozone, and heat. A variety of elements including an EPDM rubberbase has been studied to attain pleasing designs and enhance functionssuch as slidability.

EPDM rubber is favorably applied to, for example, weather strips.Weather strips are attached to the periphery of door openings ofautomobiles to seal the openings so as to keep out rainwater, dust andnoise.

EPDM rubber itself is, however, black and not visually pleasing.Accordingly, the EPDM rubber base is usually covered with an ornamentallayer such as polyester or nylon cloth which has a color well matchedwith the automobile interior.

The manufacturing process for the rubber layered structure having anEPDM rubber base and a surface layer includes, for example, extrusionand vulcanization of the EPDM rubber base, buffing and de-greasing ofthe EPDM rubber base, coating with a primer and an adhesive, drying ofthe adhesive, application of the surface layer, and solidification ofthe adhesive.

The conventional process requires a number of steps noted above whichresults in a long production line, thus causing low productivity andhigh cost.

JAPANESE LAID-OPEN PATENT PUBLICATION No. Sho-58-158216 proposes amethod in which a solvent adhesive including ethylene vinyl alcohol(EVA), nylon, or polyester is first applied on the surface on one sideof a surface member. The adhesive side of the surface member is placedupon an extruded main body immediately after extrusion forming and isfurther pressed thereon with a roller. The internal heat of the extrudedmain body melts the adhesive, and the surface member is accordinglystuck to the extruded main body. This method, however, has certaindisadvantages when used with such materials as an EPDM rubber basebecause no adhesives can securely stick to both the EPDM rubber base andsurface layer material such as polyester.

Besides being used for weather strips to seal door openings, EPDM-rubberis also used for a weather strip between a door sash and a window glass,which is generally called a glass run. A member for enhancingslidability of glass is stuck to a portion of the glass run facing thewindow glass, or alternatively, the portion is covered with a slidablematerial or flocking so as to enhance the slidability of the windowglass. This rubber layered structure has the same problems as statedabove for other weather strips, that is, low productivity and pooradhesive strength.

SUMMARY OF THE INVENTION

An object of the present invention is to form a rubber layered structurehaving good adhesive strength without the troublesome steps of buffingand applying an adhesive.

The present invention is directed to a rubber layered structurecomprising: an EPDM rubber base; and a laminated film comprising a firstlayer of an olefin resin with polar functional groups disposed on theEPDM rubber base, and a second layer of a polar thermoplastic resindisposed on the first layer, wherein the first layer is stuck to theEPDM rubber base by melting and resolidifying of the first layer.

According to an aspect of the present invention, the second layerincludes an ornamental surface layer.

According to another aspect of the present invention, the rubber layeredstructure further comprises an ornamental surface layer disposed on thelaminated film, wherein the ornamental surface layer is stuck to theEPDM rubber base with the laminated film. Specifically, the ornamentalsurface layer adheres to the EPDM rubber base layer by melting andre-solidifying the laminated film.

According to a preferred embodiment, the rubber layered structure is aweather strip for sealing the periphery of an opening of an automobilebody and the ornamental surface layer faces the interior of theautomobile. According to another preferred embodiment, the rubberlayered structure is a glass run for sealing and guiding a window glassof an automobile door, and the glass run further comprises a surfacelayer for reducing sliding resistance of the window glass. Specifically,the surface layer is stuck to the EPDM rubber base with the laminatedfilm by melting and re-solidifying the laminated film.

Preferably, the second layer comprises polyester resin. The ornamentalsurface layer is polyester fabric. Furthermore, the surface of thesurface layer can be flocked.

The present invention is further directed to a method of forming therubber layered structure, comprising the steps of: (a) preparing alaminated film comprising a first layer of an olefin resin with polarfunctional groups disposed on the EPDM rubber base, and a second layerof a polar thermoplastic resin disposed on the first layer; (b) formingan EPDM rubber base by extrusion; (c) vulcanizing the EPDM rubber base;and (d) attaching the laminated film to the EPDM rubber base by meltingand re-solidifying at least part of the laminated film. The heat formelting the laminated film is obtained from the heat in the EPDM rubberbase remaining from the vulcanizing.

According to another embodiment of the present invention, at theattaching step (d), the laminated film is pressed by a roller onto theheated EPDM rubber base after the vulcanizing step, whereby theornamental surface layer becomes stuck to the rubber base.

According to another embodiment of the present invention, the rubberlayered structure is a glass run for sealing and guiding a window glassof the automobile door. The glass run further comprises a surface layerfor reducing the sliding resistance of the window glass. Specifically,the surface layer is stuck to the EPDM rubber base with the laminatedfilm by melting and re-solidifying of the laminated film at theattaching step (d).

According to another embodiment of the present invention, the surfacelayer is stuck to the laminated film during the preparing step (a), andat the attaching step (d) the surface layer with the laminated film ispressed by a roller onto the heated EPDM rubber base after thevulcanizing step, whereby the surface layer is stuck by the laminatedfilm to the EPDM rubber base.

These and other objects, features, aspects and advantages of the presentinvention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a cross sectional view showing a rubber layered structureembodying the invention;

FIG. 1B is a cross sectional view showing a modification of the rubberlayered structure;

FIG. 2 is an explanatory view illustrating the production line for themanufacturing process of the rubber layered structure;

FIG. 3 is an explanatory view illustrating an automobile exterior;

FIG. 4 is a cross-sectional view showing a weather strip embodying theinvention;

FIG. 5 is an explanatory view illustrating a production line formanufacturing the weather strip;

FIG. 6 is a cross-sectional view showing a weather strip prepared byextrusion forming;

FIG. 7 is an explanatory view illustrating a peeling test of the weatherstrip;

FIG. 8 is a cross-sectional view showing a glass run according toanother embodiment of the invention;

FIG. 9 is an explanatory view illustrating a production line formanufacturing the glass run;

FIG. 10 is a cross-sectional view showing the glass run produced byextrusion forming;

FIG. 11 is a cross-sectional view showing a slidability test of theglass run;

FIG. 12 is a perspective view illustrating the slidability test of theglass run; and

FIG. 13 is a cross-sectional view showing a glass inner member in awindow sealing assembly according to a further embodiment of theinvention.

DESCRIPTION OFT HE PREFERRED EMBODIMENTS (I) Rubber layered structure

FIG. 1A is a cross-sectional view of a rubber layered structureembodying the invention. A rubber layered structure 1 includes an EPDMrubber base 5 and a surface layer 9, which adheres to the EPDM rubberbase 5 by a laminated film 7. The laminated film 7 includes a first film11 on the EPDM rubber base 5 and a second film 13 on the first film 11.

EPDM rubber is ethylene- propylene non-conjugated diene copolymer. EPDMrubber can be produced in the following manner. A slight amount ofnon-conjugated diene such as ethylidene norbornene dicyclopentadiene,1,4-hexadiene is added to ethylene and propylene. The mixture is thencopolymerized to have double bonds in side chains for sulfurvulcanization. EPDM rubber can also include a reinforcing filler such ascarbon black or white filler, a plasticizer, a sliding agent, and avulcanizing agent.

The first film 11 is prepared by introducing polar functional groupsinto a non-polar olefin resin. The first film 11 hence has excellentadhesion to EPDM rubber by properties of the olefin resin and alsoattains sufficient adhesion to polyester or nylon resin by properties ofthe polar functional groups. Such polar functional groups can includecarboxyl, hydroxyl, amino, halogen, and acrylic groups. Examples ofcommercially available materials for the first film 11 include thosesold under the trademark of ADMER by Mitsui Petrochemical Industries,Ltd., BONDFARS by Sumitomo Chemical Co., Ltd., and MODIC by MitsubishiPetrochemical Co., Ltd.

The second film 13 is made of a polar thermoplastic resin. The secondfilm 13 hence has sufficient adhesion to the first film 11 as well as anon-metal member such as a polyester sheet or cloth, or a metal membersuch as a metal foil or vacuum-evaporated metal film. The second film 13can be composed of nylon (N(PA)), polyethylene (PE), polypropylene (PP),polystyrene (PS), poly(vinyl alcohol) (PVA), poly(vinyl chloride) (PVC),poly(vinylidene chloride) (PVDC), ethylene-vinyl alcohol copolymer, orIONOMAER. Copolymerized polyester resins are preferably used for thesecond film 13 and an example of such resins is sold under the trademarkof CHEMIT R-248 by Toray Industries, Inc. The surface layer 9 iscomposed of a non-metal material or metal such as an aluminum foil or anickel chromium vacuum-evaporated film. Alternatively, the surface layer9 is composed of a non-metal material having adhesion to the second film13: for example, fabrics such as polyester, or resin sheets such aspolyvinyl chloride (PVC), nylon, and urethane.

FIG. 2 schematically illustrates a production line for the rubberlayered structure 1.

Before continuous processes on the production line, the laminated film 7can be prepared by any known method, for example, extrusion lamination,dry lamination, wet lamination, hot-melt lamination, or double layerinflation. The extrusion lamination is, however, favorable. In suchextrusion lamination, molten resin materials for the first film 11 andthe second film 13 are simultaneously extruded from a T-shaped diemounted on the end of an extruder so as to form wide laminated film. Thedry lamination is also a favorable method, wherein two films separatelyextruded are united with an adhesive in a subsequent step.

According to the continuous process shown in FIG. 2, first, anunvulcanized solid rubber material of EPDM 21 is extruded as an extrudedbody 6, which forms the EPDM rubber base 5, with an extruder 23.

The extrusion extruded body 6 is then passed through a vulcanizationapparatus 25 at temperatures between 180 degrees C. and 240 degrees C.which are favorable for vulcanization of EPDM rubber.

The surface layer 9 with the laminated film 7 previously stuck hereto iswound around a roller 27. The band of the layer and the film 7 issuccessively fed out while being pressed onto the EPDM rubber base 5with a pressure roller 29. Adhesion occurs immediately aftervulcanization of the EPDM rubber base 5 to make use of the heat of theEPDM rubber base 5. Accordingly, the laminated film 7 is melted andre-solidified, so that the surface layer 9 is stuck to the EPDM rubberbase 5.

Alternatively, the laminated film 7 and the surface layer 9 are woundabout respective rollers 27 and 30 as shown in the twodot line of FIG.2. The laminated film 7 and the surface layer 9 are simultaneously fedout, and the EPDM rubber base 5 and the surface layer 9 are then unitedby the laminated film 7.

After completion of the above processes, the layered band is cooled andeither cut or bent to a desired shape so as to form the rubber layeredstructure 1.

In the above embodiment, the laminated film 7, which is used to make thesurface layer 9 adhere to the EPDM rubber base 5, includes the firstfilm 11 of a non-polar olefin resin with polar functional groups and thepolar second film 13. The first film 11 adheres to the EPDM rubber base5 because of its affinity with EPDM rubber which is olefin rubber, andthe polar second film 13 securely adheres to the surface layer 9 becauseof its polarity. By this means, the surface layer 9 securely adheres tothe EPDM rubber base 5.

The embodiment described above has the following advantageous effects.The embodiment causes the surface layer 9 to adhere to the EPDM rubberbase 5 by making use of heat due to vulcanization on the continuousproduction line. Namely, the process in the embodiment eliminates theneed for a heating process to melt the laminated films 7, therebyimproving productivity. The process makes use of thermal energy left inthe EPDM rubber base 5 due to the vulcanization, thus saving energy.Furthermore, the embodiment does not require labor-consuming andtime-consuming processes such as buffing and application of an adhesive,thus attaining a shorter production line and simplified equipment. Theembodiment utilizes fusion of the EPDM rubber base and the surface layerby the laminated film 7, and thus does not require any adhesive, furtherreducing the cost.

Although the rubber layered structure 1 in this embodiment includes thesurface layer 9 as an ornamental layer, in another embodiment, the layer9 can be omitted and the second film 13 can be used as the surface layersuch as in FIG. 1B.

II) Weather strip

FIG. 3 is an explanatory view illustrating an automobile exterior wherea weather strip door opening trim (hereinafter referred to as weatherstrip) embodying the present invention is used. A weather strip 31 isattached to the periphery of a door opening 35 of an automobile body 33.

FIG. 4 is a cross-sectional view of the weather strip 31. A U-shapedsolid EPDM rubber base 37 is pressed and held to a flange (not shown) ofthe door opening 35 by a lip 39 of the EPDM rubber base 37. An insertionplate 41 is embedded in the EPDM rubber base 37.

An ornamental layer 43 adheres to the surface of the EPDM rubber base 37by means of a laminated film 42. The ornamental layer 43 faces theinterior of the automobile. A hollow sealing member 45 made of EPDMsponge rubber is integrally formed on the side of the EPDM rubber base37.

FIG. 5 illustrates a production line used in manufacturing the weatherstrip 31.

First, an extruded body 59 shown in FIG. 6 was formed by extrusion witha cross-head extruder 51. Unvulcanized solid rubber material of EPDMsupplied from a cylinder 53, unvulcanized sponge rubber material of EPDMsupplied from another cylinder 55, and a core plate 57 forming theinsertion plate 41 are simultaneously extruded at a speed of 5 m/min.

The composition of EPDM rubber used in this embodiment is, as follows:

    ______________________________________                                        Constituents    Amounts (parts by weight)                                     ______________________________________                                        EPDM            100.                                                          MAF carbon black                                                                              130.                                                          Paraffin process oil                                                                          100.                                                          Zinc white      5.                                                            Stearic acid    1.                                                            Dehydrating agent (CaO)                                                                       5.                                                            Vulcanization accelerator                                                                     3.5                                                           Sulfur          2.                                                            ______________________________________                                    

EPDM rubber used here is sold under the trademark of JSREP 57C by JapanSynthetic Rubber Co., Ltd.

EPDM sponge rubber material includes EPDM rubber and a foaming agent.The core plate 57 is an iron plate.

The extruded body 59 was then vulcanized at a temperature of 200 degreesC. for five minutes. Specifically, the extruded body 59 was passedthrough a microwave (ultra high frequency: UHF) heater 61 for heatingand a hot blast vulcanizing unit (HAV) 63 for maintaining thetemperature.

In the subsequent adhesion process, the ornamental layer 43 with thelaminated film 42 previously attached thereto was fed out of a roller65, and pressed onto the EPDM rubber base 37 with a pressure roller 67by making use of the remaining heat left over from vulcanization.Accordingly, the ornamental layer 43 adheres to the extruded body 59.

In this embodiment, the laminated film 42 includes: a first layer of 50micrometer thick, consisting of olefin resin sold under the trademark ofADMER by Mitsui Petrochemical Industries, Ltd.; and a second layer whichis 30 micrometer thick, consisting of a copolymerized polyester resinsold under the trademark of CHEMIT R-248 by Toray Industries, Inc.

The ornamental layer 43 is mainly composed of polyester fabric.

The layered structure including the ornamental layer 43 and the extrudedbody 59 was cooled by a cooler 69 and bent to a U-shape by a benderapparatus 71 to form the weather strip 31 shown in FIG. 4.

The weather strip 31 thus manufactured was kept at room temperature fortwenty-four hours and then tested for peeling.

A 5 mm-wide test piece 73 including a surface layer 77 adhering to alaminated film 76 was cut out from the weather strip 31 as shown in FIG.7. The free end of the surface layer 77 was pulled against the EPDMrubber base 75 in a direction shown by the arrow at a speed of 100mm/min. As a result, the EPDM rubber base 75 broke at the load of 2.5kg/5 mm, but the adhesion between the surface layer 77 and the EPDMrubber base 75 was maintained.

(III) Glass run

FIG. 3 also shows an example of glass runs. A glass run 101 is fixed tothe periphery of a window opening of the door 36 of the automobile body33.

FIG. 8 is a cross-sectional view of the glass run 101. A U-shaped solidEPDM rubber base 103 is attached to a framework (not shown) of the door36. The EPDM rubber base 103 has a groove 106 into which a window glass38 can be inserted. The groove 106 is defined by the inner bottomportion 107 of the EPDM rubber base 103 and L-shaped inner lip portions116 of the EPDM rubber base 103.

Smooth sliding layers 113a and 113b for enhancing slidability of thewindow glass adhere to the bottom portion 107 and the inner lip portions116 by means of laminated films 111a and 111b, respectively.

FIG. 9 illustrates a production line used in manufacturing the glass run101.

An extruded body 115 shown in FIG. 10 was formed by the extrusion of anunvulcanized EPDM solid rubber material by an extruder 52 from acylinder 54.

The extruded body 115 was vulcanized by passing through the microwaveheater 61 and the hot blast heater 63. The layers 113a and 113b werethen stuck to the EPDM rubber base 103 by the laminated film 111a and111b by making use of the remaining heat from vulcanization. The layeredstructure including the extruded body 115 and the surface layers 113aand 113b were cooled by the cooler 69 to form the glass run 101 of FIG.8.

The glass run 101 thus constructed was kept at room temperature fortwenty-four hours, and the following tests were carried out.

(1) Adhesion test (180 degree-peeling)

Part of the glass run 101 was cut off as a test piece in the same manneras the weather strip 31 described above, and similar results wereobtained. Namely, the EPDM rubber base 103 broke at the load of 2.5kgf/5 mm while the adhesion between the surface layer 113a or 113b andthe EPDM rubber base 103 was maintained.

(2) Slidability test

As shown in FIGS. 11 and 12, the glass run 101 was attached to aframework 121. A glass plate 123 was slid at a speed of 100 mm/min inthe groove 106 while pressed downward at a load of 1 kgf. The slidingresistance was 0.2 kgf/50 mm, which is no more than is obtained withconventional flocking.

(3) Abrasion test

The glass 123 was slid in a direction shown by the arrow at a stroke of100 mm for an abrasion test under the same conditions as the slidabilitytest. Peeling of the surface layer 113a or 113b was not observed evenafter ten thousand cycles of sliding, neither were there any fallenflock observed.

The present invention is applicable to a glass inner member attached toa lower window frame 36a of the door 36 for enhancing slidability of thewindow glass 38, and an opposing glass outer member. A glass innermember 131 shown in FIG. 13 includes: an EPDM rubber base 133 in whichan iron insertion plate 135 is embedded, and surface layers 139 forenhancing slidability of the window glass 38. The surface layers 139adhere to respective projecting portions of the EPDM rubber base 133 viaa laminated film 137.

The present invention is also applicable to various glass runs includinga double-channel type as well as the single-channel type shown in FIG.8.

In place of the polyester fabric in the above embodiment, the surfacelayer of the glass run can have a flocked member surface layer withshort fiber or can be processed in any way effective for reducingsliding resistance in place of the polyester fabric in the aboveembodiment.

Although the present invention has been described and illustrated indetail, it is clearly understood that the same is by way of illustrationand example only and is not to be taken by way of limitation, the spiritand scope of the present invention being limited only by the terms ofthe appended claims.

What is claimed is:
 1. A method of forming a rubber layered structurehaving a EPDM rubber base layer and a laminated film layer, comprisingthe steps of:(a) preparing a laminated film comprising a first filmlayer of a non-polar olefin resin modified by the introduction of maleicarthydride to form a modified olefin resin, said modified olefin resinbeing directly bondable to the EPDM rubber base layer, and a second filmlayer of a polar thermoplastic resin directly attached to said modifiedolefin resin first film layer; (b) extrusion-forming said EPDM rubberbase layer; (c) vulcanizing said EPDM rubber base layer; and (d)attaching and roller pressing said non-polar olefin first film layeronto said EPDM rubber base layer by melting and re-solidifying at leastsurface of said non-polar olefin first film layer with heat from saidEPDM rubber base layer remaining from said vulcanizing step.
 2. A methodaccording to claim 1, wherein said rubber layered structure is a weatherstrip for sealing an opening of an automobile body, and said laminatedfilm further comprises an ornamental surface layer.
 3. A methodaccording to claim 2, wherein said second film of said polarthermoplastic resin layer is made of a polyester resin, and saidornamental surface layer is made of a polyester fabric.
 4. A method asin claim 1, wherein said rubber layered structure is a glass run forsealing and guiding a window glass of an automobile, the method offorming a rubber layered structure includes the further step ofattaching a surface layer onto said second film layer with the surfacelayer comprising a surface for reducing sliding resistance of the windowglass.
 5. A method according to claim 4, wherein said second film layerof said polar thermoplastic resin is made of a polyester resin, and thesurface layer is made of a polyester fabric.
 6. A method according toclaim 4, wherein the surface layer is attached onto said polarthermoplastic resin layer of the laminated film layer during saidpreparing step, and wherein at said attaching and roller pressing stepsaid modified olefin first film layer is roller pressed onto at leastthe portion of the EPDM rubber base that is to contact the window glass.7. A method as in claim 1 wherein the vulcanizing step heats the EPDMrubber base layer to a temperature between about 180° C. to 240° C. andthe step of attaching and roller pressing occurs immediately followingvulcanizing.